Treatment of animal carcasses

ABSTRACT

Described is a method of sanitizing animal carcasses using aqueous streams having an antimicrobial composition added to the stream. Preferably, the antimicrobial composition includes a mixture of one or more carboxylic acids having up to 18 carbon atoms and one or more peroxycarboxylic acids having up to 12 carbon atoms, preferably a mixture of a C 2 -C 4  peroxycarboxylic acid and a C 8 -C 12  peroxycarboxylic acid. Also described is a novel antimicrobial composition adapted for sanitizing animal carcasses containing a mixture of one or more C 2 -C 4  peroxycarboxylic acids and one or more C 8 -C 12  peroxycarboxylic acids and an alpha-hydroxy mono- or dicarboxylic acid.

This application is a continuation of application Ser. No. 09/634,502,filed Aug. 9, 2000 now abandoned, which is a divisional of Ser. No.09/419,019, filed Oct. 15, 1999 now U.S. Pat. No. 6,103,286, which is adivisional of Ser. No. 09/137,242, filed Aug. 20, 1998 now U.S. Pat. No.6,010,729, which applications are incorporated herein by reference.

FIELD OF THE INVENTION

This invention generally relates to compositions and processes forcleaning or sanitizing animal carcasses during meat packing orpreparation. More specifically, this invention relates to antimicrobialcompositions and processes for cleaning and sanitizing animal carcassesthrough direct contact between the carcass and the treatment The natureof the contact between the carcass and the antimicrobial compositionsimproves antimicrobial properties. The compositions and methods reducemicrobial populations and do not affect the appearance, smell or tasteof the carcass meat.

BACKGROUND OF THE INVENTION

The cleaning of carcasses in the preparation of any food product can bean unsanitary and time consuming task. Further, without a cleaningroutine which follows an ordered process of steps to completely sanitizecarcass meat, any number of problems may arise. Carcass meat may retainpathogens or infectious microbes (E. coli) or become increasingly morecontaminated if viscera is allowed to rupture or is not properlyremoved. Further, incomplete cleaning of the carcass meat may alsoresult in the presence of infectious microbes making the meat unsuitablefor consumption.

PURAC® is a natural lactic acid produced by fermentation from sugar. Ithas a mild acid taste and is widely used in the food industry as anacidulant. PURAC® is an effective decontaminating agent for use withpoultry, beef and pork carcasses and slaughter by-products. PURAC® ismost effective at a use concentration of between 1 and 2 percent, andcan be used at several different points in the slaughter line.Application immediately after hide removal reduces the amount ofmicroorganisms entering subsequent processing steps, while treatmentsafter evisceration and prior to chilling have the greatest residualeffects. Mountney et al. also discuss the use of lactic acid to lowerbacterial counts and otherwise preserve poultry in “Acids As PoultryMeat Preservatives” in Poultry Science, 44: 582, 1965. Blankenship etal. discussed the destruction of Salmonella contaminates on fajitachicken meat in “Efficacy of Acid Treatment Plus Freezing To DestroySalmonella Contaminates Of Spice Coated Chicken Fajita Meat” in PoultryScience, Vol. 69, Supp., 1990, p. 20. Adams et al. discuss the use ofpropylene glycol, sodium lactate, and lactic acid in chill water toreduce salmonella contamination of processed broilers. (See, Effects ofVarious Chill Water Treatments on Incidents and Levels of Salmonella onProcessed Carcasses, Department of Animal and Poultry Sciences,University of Arkansas, Fayetteville). Izat et al. discuss the effectsof lactic acid on commercial broiler carcasses in reducing salmonellacounts in Poultry Science, Vol. 69, Supp. 1990, p. 152; Journal ofQuality, Vol. 13, 1990 p. 295-306; and Journal of Food Protection, Vol.52, No. 9, pp. 670-6⁷³, Sept. 1989. Avens et al. discuss thepasteurization of turkey carcasses and the reduction of salmonella usinglactic acid in Poultry Science, Vol. 51, 1972, p. 178 1. Mulder et al.in 1987 Poultry Science 66:1555-1557 reports a study of treating broilercarcasses with lactic acid, 1-cysteine and hydrogen peroxide. Thetreatment with lactic acid and hydrogen peroxide resulted in a 4-logcycle reduction in colony forming units of Salmonella typhimurium.Nevertheless, use of lactic acid resulted in a slightly changed color ofthe carcasses and all the treatments with hydrogen peroxide resulted inbleached and bloated carcasses.

Although peroxycarboxylic acids are known to be used for cleaning andsanitizing equipment and other surfaces, they have not been reported forcleaning and sanitizing animal carcasses. Holzhauer et al., U.S. Pat.No. 5,435,808, describes curing of animal hides with an acetic acid,peroxyacetic acid, hydrogen peroxide, and phosphoric acid combination.The heightened concerns of consumers over the organoleptic purity andsafety of meat products, concerns over the environmental andorganoleptic impact of many antimicrobial agents currently available, aswell as the stringent economies of the meat and poultry industry haveresulted in an ongoing need for carcass sanitizing compositions andprocesses which provide increased sanitization with organoleptic andenvironmental purity.

SUMMARY OF THE INVENTION

Accordingly the present invention, in a first aspect, provides a methodof treating animal carcasses to obtain a reduction by at least one log₁₀in surface microbial population which method includes the step oftreating said carcass with an antimicrobial composition comprising aneffective antimicrobial amount comprising at least 2 parts per million(ppm, parts by weight per each one million parts) of one or moreperoxycarboxylic acids having up to 12 carbon atoms and an effectiveantimicrobial amount comprising at least 20 ppm of one or morecarboxylic acids having up to 18 carbon atoms to reduce the microbialpopulation.

A second aspect of the invention is an antimicrobial composition adaptedfor cleaning and sanitizing animal carcasses which contains about 0.5weight percent (wt-%) to about 20 wt-% of a mixture of one or moreperoxycarboxylic acids having from 2-4 carbon atoms, and one or moreperoxycarboxylic acids having from 8-12 carbon atoms, from about 0.5wt-% to about 60 wt-% of an alpha-hydroxy mono or dicarboxylic acidhaving 3-6 carbon atoms, an effective amount of a sequestrant and aneffective amount of a hydrotrope.

A third preferred aspect of the present invention is an antimicrobialcomposition adapted for treating animal carcasses consisting of amixture of peroxyacetic and peroxyoctanoic acid in a ratio of about 10:1to about 1:1, from about 0.1 to about 10 wt-% of lactic acid, from about4 wt-% to about 10 wt-% of hydrogen peroxide and from about 0.5 wt-% toabout 1.5 wt-% of a sequestering agent.

A fourth aspect of the present invention involves a method of treatingan animal carcass to reduce a microbial population in resulting cutmeat, the method comprising the steps of spraying an aqueousantimicrobial treatment composition onto said carcass at a pressure ofat least 50 psi at a temperature of up to about 60° C. resulting in acontact time of at least 30 seconds, the antimicrobial compositioncomprising an effective antimicrobial amount comprising least 2 ppm ofone or more carboxylic acid, peroxycarboxylic acid or mixtures thereof;and achieving at least a one log₁₀ reduction in the microbialpopulation.

A fifth aspect of the present invention involves a method of treating ananimal carcass to reduce a microbial population in resulting cut meat,the method comprising the steps of placing the carcass in a chamber atatmospheric pressure; filling the chamber with condensing steamcomprising an antimicrobial composition for a short duration; andquickly venting and cooling the chamber to prevent browning of the meatcarcass; wherein the duration of the steam thermal process may be fromabout 5 seconds to about 30 seconds and the chamber temperature mayreach from about 50° C. to about 93° C.

The antimicrobial composition can be applied in various ways to obtainintimate contact with each potential place of microbial contamination.For example, it can be sprayed on the carcasses, or the carcasses can beimmersed in the composition. Additional methods include applying afoamed composition and a thickened or gelled composition. Vacuum and orlight treatments can be included, if desired, with the application ofthe antimicrobial composition. Thermal treatment can also be applied,either pre-, concurrent with or post application of the antimicrobialcomposition. We have found a preferred spray method for treatingcarcasses with compositions of the invention involving spraying thecarcass with an aqueous spray at a temperature less than about 60° C. ata pressure of about 50 to 500 psi gauge wherein the spray comprises aneffective antimicrobial amount of a carboxylic acid, an effectiveantimicrobial amount of a peroxycarboxylic acid or mixtures thereof.These sprays can also contain an effective portion of a peroxy compoundsuch as hydrogen peroxide and other ingredients such as sequesteringagents, etc. We have found that the high pressure spray action of theaqueous treatment removes microbial populations by combining themechanical action of the spray with the chemical action of theantimicrobial materials to result in a surprisingly improved reductionof such populations on the surface of the carcass. All pressures arepsig (or psi gauge). Differentiation of antimicrobial “-cidal” or“-static” activity, the definitions which describe the degree ofefficacy, and the official laboratory protocols for measuring thisefficacy are important considerations for understanding the relevance ofantimicrobial agents in compositions. Antimicrobial compositions mayeffect two kinds of microbial cell damages. The first is a truly lethal,irreversible action resulting in complete microbial cell destruction orincapacitation. The second type of cell damage is reversible, such thatif the organism is rendered free of the agent, it can again multiply.The former is termed bacteriocidal and the latter, bacteriostatic. Asanitizer and a disinfectant are, by definition, agents which provideantibacterial or bacteriocidal activity and achieve at least a five foldreduction (i.e., a five log 10 reduction) in microbial populations aftera 30 second contact time (see AOAC method 960.09).

In contrast, a preservative is generally described as an inhibitor orbacteriostatic composition that simply retards growth in a reversiblemode. For the purpose of this patent application, successful microbialreduction is achieved when the microbial populations are reduced by onelogo. In this industry, the one log₁₀ microbial population reduction isthe minimum acceptable for the processes. Any increased reduction inmicrobial population is an added benefit that provides higher levels ofprotection for processed carcass meat.

DETAILED DESCRIPTION OF THE INVENTION

The invention is a process for sanitizing animal carcasses throughtreatment with aqueous streams containing an antimicrobial composition.The dip or spray methods used for carcass cleaning as well as sanitizinganimal carcasses generally include an effective antimicrobialconcentration of one or more carboxylic acids and one or moreperoxycarboxylic acids.

A. The Sanitizing Composition

The sanitizing composition used in the method of the invention generallycontains one or more carboxylic acids and one or more peroxycarboxylicacids with a peroxygen compound such as H₂O₂. Typically, however, thecomposition contains one or more carboxylic acids, an oxidizer, and oneor more peroxycarboxylic acids depending on equilibrium. Commonly, theperoxycarboxylic acid material can be made by oxidizing a carboxylicacid directly to the peroxycarboxylic acid material which is thensolubilized in the aqueous rinse agent compositions of the invention.Further, the materials can be made by combining the unoxidized acid witha peroxygen compound such as hydrogen peroxide to generate the peracidin situ prior to blending the peroxycarboxylic acid with otherconstituents. The compositions of the invention comprises blends of thecarboxylic acid and percarboxylic acid along with other componentsincluding a peroxy source such as hydrogen peroxide. Once blended andapplied the compositions can change due to interactions between theblended materials and due to interactions in the use locus. For example,the salt component can exchange and become associated with free acidsand the peroxy source can oxidize oxidizable materials. Theanti-microbial properties arise from the blend of an acid material and aperacid material. The modification post blending and application do notchange the invention.

A carboxylic acid is an organic acid (R—COOH) which contains analiphatic group and one or more carboxyl groups. A carboxyl group isrepresented by —COOH, and is usually located at a terminal end of theacid. The aliphatic group can be a substituted or unsubstituted group.Common aliphatic substituents include —OH, —OR, —NO₂, halogen, and othersubstituents common on these groups. An example of a simple carboxylicacid is acetic acid, which has the formula CH₃COOH. A peroxycarboxylicacid is a carboxylic acid which has been oxidized to contain a terminal—COOOH group. The term peroxy acid is often used to represent aperoxycarboxylic acid. An example of a simple peroxy acid isperoxyacetic acid, which has the formula CH₃COOOH.

Generally when the peroxycarboxylic acid is formulated in accordancewith the invention a monocarboxylic acid, such as acetic acid, iscombined with an oxidizer such as hydrogen peroxide. The result of thiscombination is a reaction producing a peroxycarboxylic acid, such asperoxyacetic acid, and water. The reaction follows an equilibrium inaccordance with the following equation:

H₂O₂+CH₃COOH⇄CH₃COOOH+H₂O

wherein the pK_(eq) is 1.7.

The importance of the equilibrium results from the presence of hydrogenperoxide, the carboxylic acid and the peroxycarboxylic acid in the samecomposition at the same time. Because of this equilibrium, a mixture ofcarboxylic acid and peroxycarboxylic acid can be combined in waterwithout adding hydrogen peroxide. If permitted to approach equilibrium,the mixture will evolve hydrogen peroxide. This combination providesenhanced sanitizing with none of the deleterious environmental ororganoleptic effects of other sanitizing agents, additives, orcompositions.

The Carboxylic Acid

The first constituent of the composition used in the method of theinvention includes one or more carboxylic acids. Generally, carboxylicacids have the formula R—COOH wherein the R may represent any number ofdifferent groups including aliphatic groups, alicyclic groups, aromaticgroups, heterocyclic groups, all of which may be saturated orunsaturated. Carboxylic acids also occur having one, two, three, or morecarboxyl groups. Aliphatic groups can be further differentiated intothree distinct classes of hydrocarbons. Alkanes (or paraffins) aresaturated hydrocarbons. Alkenes (or olefins) are unsaturatedhydrocarbons which contain one or more double bonds and alkynes (oracetylenes) are unsaturated hydrocarbons containing one or more highlyreactive triple bonds. Alicyclic groups can be further differentiatedinto three distinct classes of cyclic hydrocarbons. Cycloparaffins aresaturated cyclic hydrocarbons. Cycloolefins are unsaturated cyclichydrocarbons which contain one or more double bonds whilecycloacetylenes are unsaturated cyclic hydrocarbons containing one ormore highly reactive triple bonds. Aromatic groups are defined aspossessing the unsaturated hydrocarbon ring structure representative ofbenzene. Heterocyclic groups are defined as 5 or 6 member ringstructures wherein one or more of the ring atoms are not carbon. Anexample is pyridine, which is essentially a benzene ring with one carbonatom replaced with a nitrogen atom.

Carboxylic acids have a tendency to acidify aqueous compositions inwhich they are present as the hydrogen atom of the carboxyl group isactive and may appear as a cation. The carboxylic acid constituentwithin the present composition when combined with aqueous hydrogenperoxide generally functions as an antimicrobial agent as a result ofthe presence of the active hydrogen atom. Moreover, the carboxylic acidconstituent within the invention maintains the composition at an acidicpH. The composition of the invention can utilize carboxylic acidscontaining as many as 18 carbon atoms. Examples of suitable carboxylicacids include formic, acetic, propionic, butanoic, pentanoic, hexanoic,heptanoic, octanoic, nonanoic, decanoic, undecanoic, dodecanoic, lactic,maleic, ascorbic, citric, hydroxyacetic, neopentanoic, neoheptanoic,neodecanoic, oxalic, malonic, succinic, glutaric, adipic, pimelic andsubric acid.

Carboxylic acids which are generally useful are those having one or twocarboxyl groups where the R group is a primary alkyl chain having alength of C₂ to C₅ and which are freely water soluble. The primary alkylchain is that carbon chain of the molecule having the greatest length ofcarbon atoms and directly appending carboxyl functional groups.Especially useful are mono- and dihydroxy substituted carboxylic acidsincluding alpha-hydroxy substituted carboxylic acid. A preferredcarboxylic acid is acetic acid, which produces peroxyacetic acid toincrease the sanitizing effectiveness of the materials. Acetic acid hasthe structure of the formula:

An especially preferred -hydroxy-monocarboxylic acid is lactic acid,also known as 2-hydroxypropionic acid, which is a naturally occurringorganic acid. Lactic acid has a molecular weight of 90.08 and is solublein water, alcohol, acetone, ether and glycerol. Lactic acid occursnaturally and may be produced by fermentation. Alternatively, lacticacid may be synthesized.

Lactic Acid has the Structure of the Formula

The concentration of α-hydroxy-mono-or di-carboxylic acid useful in thepresent invention generally ranges from about 0.5 wt-% to about 60 wt-%,preferably about 1 wt-% to about 20 wt-%, and most preferably from about2 wt-% to about 10 wt-%. This concentration range of lactic acid ispreferred for reasons of optimal acidity within the composition, as wellas for the optimal antimicrobial efficacy which it brings to theantimicrobial system.

Reducing the concentration of lactic acid in comparison to any givenconcentration of hydrogen peroxide will essentially reduce theantimicrobial activity of the composition. Moreover, reducing theconcentration of lactic acid may result in an increase in the pH of thecomposition and accordingly raise the potential for decreasedantimicrobial activity. In sharp contrast, increasing the concentrationof lactic acid within the present composition may tend to increase theantimicrobial activity of the composition. Furthermore, increasing theconcentration of lactic acid in the composition of the present inventionwill tend to decrease the pH of the composition. Preferably, the pH ofthe present composition will be 4 or less with a generally preferred pHin the composition being between 1.5 and 3.75, and a pH between about 2and 3.5 being most preferred.

Generally, the concentration of carboxylic acid within the compositionused in the process of the invention ranges from about 0.5 wt-% to about60 wt-%, preferably from about 10 wt-% to about 60 wt-%, and mostpreferably from about 20 wt-% to about 50 wt-%.

The Peroxycarboxylic Acid

Another principle component of the antimicrobial composition of theinvention is an oxidized carboxylic acid. This oxidized orperoxycarboxylic acid provides heightened antimicrobial efficacy whencombined with hydrogen peroxide and the monocarboxylic acid in anequilibrium reaction mixture. Peroxycarboxylic acids generally have theformula R(CO₃H)_(n), where R is an alkyl, arylalkyl, cycloalkyl,aromatic or heterocyclic group, and n is one or two and named byprefixing the parent acid with peroxy. An alkyl group is a paraffinichydrocarbon group which is derived from an alkane by removing onehydrogen from the formula. The hydrocarbon group may be either linear orbranched, having up to 12 carbon atoms. Simple examples include methyl(CH₃) and ethyl (CH₂CH₃). An arylalkyl group contains both aliphatic andaromatic structures. A cycloalkyl group is defined as a cyclic alkylgroup.

While peroxycarboxylic acids are not very stable, their stabilitygenerally increases with increasing molecular weight. Thermaldecomposition of these acids may generally proceed by free radical andnonradical paths, by photodecomposition or radical-induceddecomposition, or by the action of metal ions or complexes.Peroxycarboxylic acids may be made by the direct, acid catalyzedequilibrium action of 30-98 wt-% hydrogen peroxide with the carboxylicacid, by autoxidation of aldehydes, or from acid chlorides, acidanhydrides, or carboxylic anhydrides with hydrogen or sodium peroxide.

Peroxycarboxylic acids useful in this invention include peroxyformic,peroxyacetic, peroxypropionic, peroxybutanoic, peroxypentanoic,peroxyhexanoic, peroxyheptanoic, peroxyoctanoic, peroxynonanoic,peroxydecanoic, peroxyundecanoic, peroxydodecanoic, peroxylactic,peroxymaleic, peroxyascorbic, peroxyhydroxyacetic, peroxyoxalic,peroxymalonic, peroxysuccinic, peroxyglutaric, peroxyadipic,peroxypimelic and peroxysubric acid and mixtures thereof. Theseperoxycarboxylic acids have been found to provide good antimicrobialaction with good stability in aqueous streams. In a preferredembodiment, the composition of the invention utilizes a combination ofseveral different peroxycarboxylic acids. Preferably, the compositionincludes one or more small C₂-C₄ peroxycarboxylic acids and one or morelarge C₈-C₁₂ peroxycarboxylic acids. Especially preferred is anembodiment in which the small peroxycarboxylic acid is peroxyacetic acidand the large acid is either peroxyoctanoic acid or peroxydecanoic acid.

Peroxyacetic acid is a peroxycarboxylic acid with a structure as giventhe formula:

wherein the peroxy group, —O—O—, is considered a high energy bond.Generally, peroxyacetic acid is a liquid having an acrid odor and isfreely soluble in water, alcohol, ether, and suliric acid. Peroxyaceticacid may be prepared through any number of means known to those of skillin the art including preparation from acetaldehyde and oxygen in thepresence of cobalt acetate. A 50% solution of peroxyacetic acid may beobtained by combining acetic anhydride, hydrogen peroxide and sulfuricacid. Other methods of formulation of peroxyacetic acid include thosedisclosed in U.S. Pat. No. 2,833,813, which is incorporated herein byreference.

Peroxyoctanoic acid has the structure of the formula:

Peroxydecanoic acid has the structure of the formula:

The preferred peroxycarboxylic acid materials of the invention can beused to increase the sanitizing effectiveness of the materials. When ablended acid is used, the peroxycarboxylic acid is blended inproportions that range from about 10:1 to about 1:1 parts of C₂-C₄peroxycarboxylic acid per part of C₈-C₁₂ peroxycarboxylic acid.Preferably, peroxyacetic acid is used at a ratio of about 8 parts perpart of peroxyoctanoic acid.

The above sanitizer material can provide antibacterial activity to therinse aid sanitizers of the invention against a wide variety ofmicroorganisms such as gram positive (for example, Staphylococcusaureus) and gram negative (for example, Escherichia coli)microorganisms, yeast, molds, bacterial spores, viruses, etc. Whencombined, the above peroxy acids can have enhanced activity compared tothe low molecular weight peroxy acids alone.

Generally, the concentration of peroxycarboxylic acid within thecomposition used in the process of the invention ranges from about 0.5wt-% to about 20 wt-%, preferably from about 2 wt-% to about 15 wt-%,and most preferably from about 4 wt-% to about 12 wt-%.

The Oxidizer

The composition used in the method of the invention also includes anoxidizer. Any number of oxidizers may be used as a precursor to theformation of a peroxycarboxylic acid as well as to provide furtherphysical effervescent or agitation action to the composition of theinvention. Preferably, the antimicrobial composition of the inventioncontains hydrogen peroxide. Hydrogen peroxide (H₂O₂) has a molecularweight of 34.014 and it is a weakly acidic, clear, colorless liquid. Thefour atoms are covalently bonded in a non-polar structure:

Generally, hydrogen peroxide has a melting point of −0.41° C., a boilingpoint of 150.2° C., a density at 25° C. of 1.4425 grams per cm³, and aviscosity of 1.245 centipoise at 20° C.

Hydrogen peroxide in combination with the carboxylic acid andperoxycarboxylic acid provides a surprising level of antimicrobialaction against microorganisms, even in the presence of high loadings oforganic sediment. Additionally, hydrogen peroxide provides aneffervescent action which may irrigate any surface to which it isapplied. Hydrogen peroxide works with a mechanical flushing action onceapplied which further plains the surface of application. An additionaladvantage of hydrogen peroxide is the food compatibility of thiscomposition upon use and decomposition. For example, combinations ofperoxyacetic acid and hydrogen peroxide result in acetic acid, water,and oxygen upon decomposition. All of these constituents are foodproduct compatible. Generally, the concentration of hydrogen peroxidewithin the composition used in the process of the invention ranges fromabout 1 wt-% to about 35 wt-%, preferably from about 2 wt-% to about 25wt-%, and most preferably from about 5 wt-% to about 10 wt-%. Thisconcentration of hydrogen peroxide is most preferred as providingoptimal antimicrobial effect.

These concentrations of hydrogen peroxide may be increased or decreasedwhile still remaining within the scope of the present invention. Forexample, increasing the concentration of hydrogen peroxide may increasethe antimicrobial efficacy of the claimed invention. Furthermore,increasing the hydrogen peroxide concentration may reduce the need tostabilize the hydrogen peroxide within the composition. Specifically,increasing the hydrogen peroxide concentration in the composition mayprovide a composition which has extended shelf life.

In contrast, decreasing the concentration of hydrogen peroxide maydecrease the antimicrobial efficacy of the composition and necessitatethe use of an increased concentration of carboxylic acid. Moreover,decreasing the concentration of hydrogen peroxide may necessitate theuse of some stabilizing agent to ensure that the composition of thepresent invention will remain stable and efficacious over the intendedtime period.

In all, altering the concentration of the oxidizing agent will effectthe equilibrium mix of the peroxycarboxylic acid used in the invention.

The Carrier

The composition of the invention also includes a carrier. The carrierfunctions to provide a reaction medium for the solubilization ofconstituents and the production of peroxycarboxylic acid as well as amedium for the development of an equilibrium mixture of oxidizer,peroxycarboxylic acid, and carboxylic acid. The carrier also functionsto deliver and wet the antimicrobial composition of the invention to theintended substrate. To this end, the carrier may contain any componentor components which will facilitate the functions. Generally, thecarrier consists of water which is an excellent solubilizer and mediumfor reaction and equilibrium. The carrier may also include any number ofconstituents such as various organic compounds which facilitate thefunctions provided above. Organic solvents which have been found usefulinclude simple alkyl alcohols such as ethanol, isopropanol, n-propanol,and the like. Polyols are also useful carriers in accordance with theinvention, including propylene glycol, polyethyleneglycol, glycerol,sorbitol, and the like. Any of these compounds may be used singly or incombination with other organic or inorganic constituents or, incombination with water or in mixtures thereof. Preferably, the carrierconsists of from about 1 wt-% to about 60 wt-% of an organic solvent.

Generally, the carrier makes up a large portion of the composition ofthe invention and may essentially be the balance of the compositionapart from the active antimicrobial composition adjuvants, and the like.Here again, the carrier concentration and type will depend upon thenature of the composition as a whole, the environmental storage andmethod of application including concentration of the antimicrobialagent, among other factors. Notably the carrier should be chosen andused at a concentration which does not inhibit the antimicrobialefficacy of the act in the composition of the invention.

B. Adjuvants

The composition of the invention may also optionally include any numberof adjuvants which are stable in an oxidizing environment, and addbeneficial properties of stability, sequestration, sheeting and rinsing,etc. These adjuvants may be preformulated with the sanitizing agent ofthe invention or added to the system simultaneously, or even after, theaddition of the sanitizing agent of the invention.

Chelating Agent

The sanitizing agents of the invention may also contain a polyvalentmetal complexing or chelating agent that aids in reducing the harmfuleffects of hardness components and service water and improves productstability. The typically harmful effects of calcium, magnesium, iron,manganese, etc., ions present in service water can interfere with theaction of either the washing compositions or rinsing compositions or cantend to decompose the active peroxygen sanitizer materials. Thechelating agent or sequestering agent can effectively complex and removesuch ions from inappropriate interaction with active ingredients thusincreasing sanitizing agent performance.

Both organic and inorganic chelating agents may be used. Inorganicchelating agents include such compounds as sodium tripolyphosphate andother higher linear and cyclic polyphosphate species. Organic chelatingagents include both polymeric and small molecule chelating agents.Polymeric chelating agents commonly comprise polyanionic compositionssuch as polyacrylic acid compounds. Amino phosphates and phosphonatesare also suitable for use as chelating agents in the compositions of theinvention and include ethylene diamine (tetramethylene phosphonates),nitrilotrismethylene phosphates, diethylenetriamine (pentamethylenephosphonates). These amino phosphonates commonly contain alkyl oralkaline groups with less than 8 carbon atoms.

Preferred chelating agents for use in this invention include improvedfood additive chelating agents such as disodium salts of ethylenediamine tetraacetic acid or the well known phosphonates sold in the formof DEQUEST® materials, for example, 1-hydroxyethylidene-1,1-iphosphonicacid, etc. The phosphonic acid may also comprise a low molecular weightphosphonopolycarboxylic acid such as one having about 24 carboxylic acidmoieties and about 1-3 phosphonic acid groups. Such acids include1-phosphono-1-methylsuccinic acid, phosphonosuccinic acid and2-phosphonobutane-1,2,4tricarboxylic acid. Another organic phosphonicacid is (CH₃C(PO₃H₂)₂OH), available from Monsanto Industrial ChemicalsCo., St. Louis, Mo., as DEQUEST® 2010, (which is a 58-62% aqueoussolution; amino (tri(methylenephosphonic acid)] (N[CH₂PO₃H]₃), availablefrom Monsanto as DEQUEST® 2000, as a 50% aqueous solution;ethylenediamine [tetra(methylenephosphonic acid)] available fromMonsanto as DEQUEST® 2041, as a 90% solid acid product; and2-phosphonobutane-1,2,4-tricarboxylic acid available from Mobay ChemicalCorporation, Inorganic Chemicals Division, Pittsburgh, Pa., as BayhibitAM, as a 45-50% aqueous solution.

The above-mentioned phosphonic acids can also be used in the form ofwater soluble acid salts, particularly the alkali metal salts, such assodium or potassium; the ammonium salts or the alkylol amine salts wherethe alkylol has 2 to 3 carbon atoms, such as mono-, di-, ortriethanolamine salts. If desired, mixtures of the individual phosphonicacids or their acid salts can also be used.

The concentration of chelating agent useful in the present inventiongenerally ranges from about 0.01 to about 10 wt-%, preferably from about0.1 to about 5 wt-%, most preferably from about 0.5 to about 2 wt-%.

Hydrotrope

The sanitizing agent of the invention may also include a hydrotropecoupler or solubilizer. Such materials can be used to ensure that thecomposition remains phase stable and in a single highly active aqueousform. Such hydrotrope solubilizers or couplers can be used atcompositions which maintain phase stability but do not result inunwanted compositional interaction.

Representative classes of hydrotrope solubilizers or coupling agentsinclude an anionic surfactant such as an alkyl sulfate, an alkyl oralkane sulfonate, a linear alkyl benzene or naphthalene sulfonate, asecondary alkane sulfonate, alkyl ether sulfate or sulfonate, an alkylphosphate or phosphonate, dialkyl sulfosuccinic acid ester, sugar esters(e.g., sorbitan esters) and a C₈₋₁₀ alkyl glucoside.

Preferred coupling agents for use in the rinse agents of the inventioninclude n-octane sulfonate and aromatic sulfonates such as an alkylbenzene sulfonate (e.g., sodium xylene sulfonate or naphthalenesulfonate). Many hydrotrope solubilizers independently exhibit somedegree of antimicrobial activity at low pH. Such action adds to theefficacy of the invention but is not a primary criterion used inselecting an appropriate solubilizing agent. Since the presence of theperoxycarboxylic acid material in the proteinated neutral state providesbeneficial biocidal or sanitizing activity, the coupling agent should beselected not for its independent antimicrobial activity but for itsability to provide effective single phase composition stability in thepresence of substantially insoluble peroxycarboxylic acid materials andthe more soluble compositions of the invention.

Generally, any number of surfactants may be used consistent with thepurpose of this constituent.

Anionic surfactants useful with the invention include alkylcarboxylates, linear alkylbenzene sulfonates, paraffin sulfonates andsecondary n-alkane sulfonates, sulfosuccinate esters and sulfated linearalcohols.

Zwitterionic or amphoteric surfactants useful with the invention includeβ-N-alkylaminopropionic acids, n-alkyl-β-iminodipropionic acids,imidazoline carboxylates, n-alky-Iletaines, amine oxides, sulfobetainesand sultaines.

Nonionic surfactants useful in the context of this invention aregenerally polyether (also known as polyalkylene oxide, polyoxyalkyleneor polyalkylene glycol) compounds. More particularly, the polyethercompounds are generally polyoxypropylene or polyoxyethylene glycolcompounds. Typically, the surfactants useful in the context of thisinvention are synthetic organic polyoxypropylene (PO)-polyoxyethylene(EO) block copolymers. These surfactants have a diblock polymercomprising an EO block and a PO block, a center block ofpolyoxypropylene units (PO), and having blocks of polyoxyethylene gratedonto the polyoxypropylene unit or a center block of EO with attached POblocks. Further, this surfactant can have further blocks of eitherpolyoxyethylene or polyoxypropylene in the molecule. The averagemolecular weight of useful surfactants ranges from about 1000 to about40,000 and the weight percent content of ethylene oxide ranges fromabout 10-80% by weight.

Also useful in the context of this invention are surfactants includingalcohol alkoxylates having EO, PO and BO blocks. Straight chain primaryaliphatic alcohol alkoxylates can be particularly useful as sheetingagents. Such alkoxylates are also available from several sourcesincluding BASF Wyandotte where they are known as “Plurafac” surfactants.A particular group of alcohol alkoxylates found to be useful are thosehaving the general formula R-(EO)_(m)-(PO)_(n). wherein m is an integerof about 2-10 and n is an integer from about 2-20. R can be any suitableradical such as a straight chain alkyl group having from about 6-20carbon atoms.

Other useful nonionic surfactants of the invention include cappedaliphatic alcohol alkoxylates. These end caps include but are notlimited to methyl, ethyl, propyl, butyl, benzyl and chlorine.Preferably, such surfactants have a molecular weight of about 400 to10,000. Capping improves the compatibility between the nonionic and theoxidizers hydrogen peroxide and peroxycarboxylic acid, when formulatedinto a single composition. Other useful nonionic surfactants arealkylpolyglycosides.

Another useful nonionic surfactant of the invention is a fatty acidalkoxylate wherein the surfactant comprises a fatty acid moiety with anester group comprising a block of EO, a block of PO or a mixed block orheteric group. The molecular weights of such surfactants range fromabout 400 to about 10,000, a preferred surfactant has an EO content ofabout 30 to 50 wt-% and wherein the fatty acid moiety contains fromabout 8 to about 18 carbon atoms.

Similarly, alkyl phenol alkoxylates have also been found usefull in theinvention. Such surfactants can be made from an alkyl phenol moietyhaving an alkyl group with 4 to about 18 carbon atoms, can contain anethylene oxide block, a propylene oxide block or a mixed ethylene oxide,propylene oxide block or heteric polymer moiety. Preferably suchsurfactants have a molecular weight of about 400 to about 10,000 andhave from about 5 to about 20 units of ethylene oxide, propylene oxideor mixtures thereof.

The concentration of hydrotrope useful in the present inventiongenerally ranges from about 0.1 to about 20 wt-%, preferably from about0.5 to about 10 wt-%, most preferably from about 1 to about 4 wt-%.

Thickening/Gelling Agents

Thickeners useful in the present invention are those which do not leavecontaminating residue on the surface of application, i.e., constituentswhich are incompatible with food or other sensitive products in contactareas.

Generally, thickeners which may be used in the present invention includenatural gums such as xanthan gum. Also useful in the present inventionare cellulosic polymers, such as carboxymethyl cellulose. Generally, theconcentration of thickener use in the present invention will be dictatedby the desired viscosity within the final composition. However, as ageneral guideline, viscosity of thickener within the present compositionranges from about 0.1 wt-% to about 1.5 wt-%, preferably from about 0.1wt-% to about 1.0 wt-%, and most preferably from about 0.1 wt-% to about0.5 wt-%.

C. Formulation

The compositions of the invention can be formulated by combining thesanitizing agent materials including other adjuvant components with thematerials that form the sanitizer composition, the carboxylic acid oracid blend, hydrogen peroxide and optionally, hydrotrope solubilizer.

The compositions can also be formulated with preformed peroxycarboxylicacids. The preferred compositions of the invention can be made by mixingthe carboxylic acid or mixture thereof with an optional hydrotropesolubilizer or coupler, reacting the mixture with hydrogen peroxide andthen adding the balance of required ingredients to provide rinsing andsanitizing action.

A stable equilibrium mixture is produced containing the carboxylic acidor blend with hydrogen peroxide and allowing the mixture to stand for1-7 days at 15° C. or more. With this preparatory method, an equilibriummixture will be formed containing an amount of hydrogen peroxide,unoxidized acid, oxidized or peroxycarboxylic acid and typicallyunmodified couplers, solubilizer, or stabilizers.

D. Use Compositions

The invention contemplates a concentrate composition which is diluted toa use solution prior to its utilization as a sanitizer. Primarily forreasons of economics, the concentrate would normally be marketed and anend user would preferably dilute the concentrate with water or anaqueous diluent to a use solution.

The general constituent concentrations of the sanitizing concentrateformulated in accordance with the invention may be found in Table 1:

TABLE 1 More Most Preferred Preferred Preferred Constituent (wt-%)(wt-%) (wt-%) H₂O₂  1-35  2-25  5-10 Peroxycarboxylic acids 0.5-20  2-15  4-12 Carboxylic acid 0.5-60  10-60 20-50 Chelating agent0.01-10   0.01-5   0.5-2   Hydrotrope 0.1-20  0.5-10  1-4 Thickeningagent 0.1-1.5 0.1-1.0 0.1-0.5 Carrier  0-97 10-90 12-65

The level of active components in the concentrate composition isdependent on the intended dilution factor and the desired activity ofthe peroxycarboxylic acid compound and the carboxylic acid.

Generally, a dilution of about 1 fluid ounce to about 0.5 to 10.0gallons of water is used for aqueous antimicrobial sanitizing solutions.The composition shown in the preferred column of the Table 1 above wouldbe used in a range from about 12.8 fluid ounce per gallon water to about1 fluid ounce per 780 gallons of water depending on the desired level ofperoxycarboxylic acid and concentration of the peroxycarboxylic acid inthe product concentrate.

Higher use dilutions can be employed if elevated use temperature(greater than 25° C.) or extended exposure time (greater than 30seconds) can be employed. In the typical use locus, the concentrate isdiluted with a major proportion of water and used for sanitizing usingcommonly available tap or service water mixing the materials at adilution ratio of about 0.1 to about 2 ounces of concentrate per gallonof water.

Aqueous antimicrobial sanitizing use solutions can include at leastabout 2 ppm, preferably about 10 to about 500 ppm, and more preferablyabout 100 to about 250 parts per million of the peroxycarboxylic acidmaterial; about 20 ppm to about 10,000 ppm, and preferably about 50 ppmto about 1,000 ppm of carboxylic acid; and about 10 to about 1,000 ppmof hydrogen peroxide. The aqueous use solution can further include atleast about 50 ppm, preferably about 500 ppm of the hydrotropesolubilizer, and have a pH in the use solution in the range of about 1to about 11 preferably about 2 to about 10.

E. Method of Use

During processing of the carcass meat, the carcasses can be contactedwith the compositions of the invention in any mode be that insures goodcontact between the carcass and the composition and at least someminimal mechanical work to result in at least a one log 10 reduction,preferably at least a two log₁₀ reduction and more preferably a threelog₁₀ reduction in the resident microbial preparation. A five log₁₀reduction in 30 seconds is a sanitizing treatment.

The invention is applicable to a wide range of possible animalcarcasses. For example, the antimicrobial compositions of the inventioncan be used on muscle meats including beef, pork, veal, buffalo or lamb,sea food including scallops, shrimp, crab, octopus, mussels, squid orlobster and poultry including chicken, turkey, ostrich, game hen, squabor pheasant.

A preferred mode is a pressure spray with the sanitizing solution of theinvention. During application of the spray solution on the carcasses,the surface of the carcasses can be moved with mechanical action,preferably agitated, rubbed, brushed, etc. Agitation may be by physicalscrubbing of the carcasses, through the action of the spray solutionunder pressure or by other means. The agitation increases the efficacyof the spray solution in killing micro-organisms, perhaps due to betterexposure of the solution into the crevasses or small colonies containingthe micro-organisms. The spray solution, before application, may also beheated to a temperature of about 15 to 20° C., preferably about 20 to50° C. to increase efficacy. After a sufficient amount of time to killthe micro-organisms on the carcasses, the spray solution may be rinsedoff the animal carcasses.

Application of the material by spray means can be accomplished using amanual spray wand application, an automatic spray of carcasses movingalong a production line using multiple spray heads to ensure completecontact or other spray means. One preferred automatic spray applicationinvolves the use of a spray booth. The spray booth substantiallyconfines the sprayed composition to within the parameter of the booth.The production line moves the carcass through the entryway into thespray booth in which the carcass is sprayed on all its exterior surfaceswith sprays within the booth. After a complete coverage of the materialand drainage of the material from the carcass within the booth, thecarcass can then exit the booth in a fully treated form. The spray boothcan comprises steam jets that can be used to apply the antimicrobialcompositions of the invention. These steam jets can be used incombination with cooling water to ensure that the treatment reaching thecarcass surface is less than 65° C., preferably less than 60° C. Thetemperature of the spray on the carcass is important to ensure that thecarcass meat is not substantially altered (cooked) by the temperature ofthe spray. The spray pattern can be virtually any useful spray pattern.

The spray can comprise a fogged material that leaves a fogging apparatusas a dispersion of fog particles in a continuous atmosphere. Such aspray has no defined pattern. The spray can have a pattern such as aconical spray in which the angle between the perimeter of the sprayranges from less than 180° to about 5°. Other spray patterns can also beuseful. We have found that one preferred spray pattern involves a “fan”spray pattern in which the spray exits the spray head in a substantiallyplanar form and the angle between the extent of the planar spray fromedge to edge is about 20° or less, preferably about 15° or less. We havefound that such a spray is preferred due to the increased mechanicalaction and efficiency of antimicrobial composition add on to thecarcass. When such a narrow angle fan spray is used in a spray cabinetenclosure to treat the carcasses, we have found that the optimumdistance between the spray head and the carcass is less than about 100centimeters, preferably about 20 to 80 centimeters, most preferablyabout 30 to 50 centimeters. Such a configuration efficiently transfersantimicrobial material to the carcass for efficient reduction of themicrobial populations.

There are a number of parameters which need to be considered if sprayingis the application method of choice. The first parameter to determine isthe pressure at which the composition is sprayed onto the carcass. Whilespray pressures as low as about 25 psi (gauge) can be used with somevaluable results, a higher spray pressure, greater than about 25, 50,100, 150 psi and more preferably greater than about 200 psi, areeffective in reducing the microbial populations due to the mechanicalaction of the spray on the carcass surface and on the microbialpopulation remaining on the surface of the carcass. The spray action isbest at temperatures less than 65° C. While a composition comprisinglactic acid has been found to be most effective at low pressure, it hasbeen discovered that equal, if not greater antimicrobial efficacy can beobtained by eliminating the lactic acid and merely increasing the sprayapplication pressure. Further, if increased spray pressures are used,the antimicrobial composition can be applied at lower temperatures,potentially resulting in substantial energy savings. Of course thereappears to be a relationship between application spray duration andantimicrobial efficacy. While spray durations of as little as about 10seconds can be used, it has been discovered that a preferred sprayduration is from about 10 to about 30 seconds. Without wishing to belimited by theory, the increased antimicrobial efficacy resulting fromthe use of the higher spray pressures is believed to be due to animprovement in penetrating the surface of the carcass, particularly anincreased ability to reach into creases and crevices on the surface ofthe carcass.

During processing of the carcass meat, the carcasses may also beimmersed into a tank containing a quantity of sanitizing solution. Thesanitizing solution is preferably agitated to increase the efficacy ofthe solution and the speed in which the solution kills micro-organismsattached to the carcasses. Agitation can be obtained throughconventional means including through ultrasonic means, aeration bybubbling air through the solution or by mechanical means, such asstrainers, paddles, brushes, or pump driven liquid jets. The sanitizingsolution may also be heated to increase the efficacy of the solution inkilling micro-organisms. It is preferable that the carcasses be immersedin the sanitizing solution after the carcasses have been eviscerated andbefore any cooling process such as a chiller tank or a chill waterspray.

In another alternative embodiment of the present invention, thecarcasses may be treated with a foaming version of the composition. Thefoam may be prepared by mixing foaming surfactants with the sanitizingsolution at time of use. The foaming surfactants could be nonionic,anionic or cationic in nature. Examples of useful surfactant typesinclude, but not limited to the following: alcohol ethoxylates, alcoholethoxylate carboxylate, amine oxides, alkyl sulfates, alkyl ethersulfate, sulfonates, quaternary ammonium compounds, alkyl sarcosines,betaines and alkyl amides. The foaming surfactant is mixed at time ofuse with the sanitizing solution. Use solution levels of the foamingagents is from about 50 ppm to about 2.0 wt-%. At time of use,compressed air is injected into the mixture, then applied to the carcasssurface through a foam application device such as a tank foamer or anaspirated wall mounted foamer.

In another alternative embodiment of the present invention, thecarcasses may be treated with a thickened or gelled version of thecomposition. In the thickened or gelled state the sanitizing solutionremains in contact with the carcass surface for longer periods of time,thus increasing the antimicrobial efficacy. The thickened or gelledsolution will also adhere to vertical surfaces. The composition or thesanitizing solution may be thickened or gelled using existingtechnologies such as: xantham gum, polymeric thickeners, cellulosethickeners or the like. Rod micelle forming systems such as amine oxidesand anionic counter ions could also be used. The thickeners or gelforming agents can be used either in the concentrated product or mixingwith the sanitizing solution, at time of use. Typical use levels ofthickeners or gel agents range from about 100 ppm to about 10 wt-%.

In another alternative embodiment of the present invention, thecarcasses may be treated with an electrostatically charged spray of thesanitizing solution. The sanitizing solution can be spray applied as acharged droplets by using conventional electrostatic spray technologiesincluding inductively charged methodologies. As charged droplets, thesanitizing solution will be attracted to opposite or differentiallycharged surfaces such as the surface of the carcass. As a result, moresanitizing solution will be applied to the carcass surface and lesssolution will miss the intended target, commonly called over-spray. Thecharged droplets will also provide an evenly distributed solution layeron the carcass surface. The charged droplet size will range from about10 microns to about 500 microns.

In another alternative embodiment of the present invention, thecarcasses may be subjected to a vacuum treatment either before applyingthe sanitizing solution, during the application of the sanitizingsolution or after applying the sanitizing solution. When the carcass issubjected to a vacuum treatment in conjunction with the application ofthe sanitizing solution, the penetration of the sanitizing solution intothe carcass substructure is enhanced. As a result, antimicrobialefficacy is improved. The amount of vacuum utilized is from about 2inches of Mercury (″Hg) to about 29 inches of Mercury (″Hg).

In another alternative embodiment of the present invention, thecarcasses may be subjected to an activating light source followingapplication of the sanitizing solution. The activating light can improvethe antimicrobial efficacy of the sanitizing solution. The light sourcecan be ultraviolet, infrared or from the visible spectrum.

The antimicrobial or sanitizing step can optionally be combined with athermal intervention process which occurs either before, during or afterthe application of the antimicrobial composition. The thermalintervention process may employ hot water or dry heat. In the case of ahot water thermal process, the carcass is enclosed in a chamber atatmospheric pressure. The chamber is filled with condensing steam(finely divided liquid water) for a short duration, quickly vented, thencooled to prevent browning of the meat carcass. The duration of thesteam thermal process may be from about 5 seconds to about 30 seconds.The chamber temperature may reach from about 50° C. to about 93° C.Similarly with dry heat, the carcass is placed in a chamber into whichheated air is directed. The air is heated from about 65° C. to about260° C. The carcass is allowed from about 5 to about 30 seconds contacttime with the heated air, the chamber is vented and the carcass iscooled.

WORKING EXAMPLES

The invention will now be described in more detail by reference to thefollowing working examples. The only proper construction of theseexamples is as nonlimiting, illustrative example showing variousformulations, stabilities, and applications of the invention.

Test Formula #1

Material Weight Percent Deionized water 53.9 Mixed Peroxycarboxylicacid¹ 4.75 Hydrogen Peroxide 6.9 Acetic Acid 25.0 Octanoic Acid 3.5Hydroxyethylidene-1,1-diphosphonic acid 0.95 Sodium Octane mixed Mono-and Di- 5.0 Sulfonate

Working Example #1

The objective of working example #1 was to determine if 0.5% and 1.0%lactic acid alone and in combination with Test Formula #1 and/or steamachieved a reduction in the bacterial flora present on prerigor beefsamples. An exposure time of 10 minutes was utilized for allapplications and testing was performed at 33° C.

Operating Procedure:

Sixteen prerigor beef samples were obtained and kept in a cooler untiltime of testing. Samples were aseptically divided in half. Eightdifferent test treatments were utilized with four replicate pieces pertreatment with the exception of the steam +0.5% lactic acid treatmentwhich only had three replicate pieces. Two cores (4.3 cm diameter) weretaken from each replicate piece before and after treatment, combinedinto 99 mL of Phosphate Buffered Dilution water, stomached for 1 minutesand then serially diluted and plated using pour plate technique.

Test Products:

1. Test Formula #1 at 200 ppm Total Peracid

2. Test Formula #1 at 200 ppm Total Peracid+0.5% Lactic Acid

3. Test Formula #1 at 200 ppm Total Peracid+1.0% Lactic Acid

4. 0.5% Lactic Acid

5. Steam Alone, followed by a sterile water rinse

6. Steam+Test Formula #1 at 200 ppm Total Peracid, followed by a sterilewater rinse

7. Steam+Test Formula #1 at 200 ppm Total Peracid+0.5% Lactic Acid,followed by a sterile water rinse

8. Steam+0.5% Lactic Acid followed by a sterile water rinse

Peracid Product Titrated Actual Titrated Peracid Test Formula #1 at 200ppm 212 ppm 200 ppm Test Formula #1 + 0.5% Lactic Acid 220 ppm 200 ppmTest Formula #1 + 1.0% Lactic Acid 192 ppm Test Formula #1 + Steam 210ppm Test Formula #1 + 0.5% Lactic Acid + Steam 220 ppm

Product Application: All product use solutions were applied by a sprayapplication for 10 seconds. This delivered approximately 150 mL ofproduct. An exposure time of 10 minutes was utilized, followed by a 10second sterile water rinse, if applicable.

Neutralizer: 99 mL of Phosphate Buffered Dilution Water DilutionsPlated: 10⁰, 10⁻¹, 10⁻² for Total Plate Count Before

10⁰, 10⁻¹ for Total Plate Count After

Plating Medium: Tryptone Glucose Extract Agar

Incubation: 26° C. for 72 hours

Steam Application Parameters Steam Alone 1st Replicate: Startingtemperature was 86° C., ending at 92° C. A 17 second exposure time wasutilized and a 10 second delay occurred prior to the sterile water rinsefor 10 seconds. 2nd Replicate: Starting temperature was high 80° C.,ending at 90+° C. 3rd & 4th Replicates: Starting temperature was 82° C.,ending at 87° C. An 8 second exposure time and a 10 second sterile waterrinse were utilized for replicates 2, 3 and 4. Test Formula #1 + 1stReplicate: Starting temperature was 82° C., Steam ending at 87° C. 2ndReplicate: Starting temperature was 80° C., ending at 84° C. 3rdReplicate: Starting temperature was 83° C., ending at 88° C. 4thReplicate: Starting temperature was 86° C., ending at 89° C. An 8 secondexposure time and a 10 second sterile water rinse were utilized for allreplicates. Test Formula #1 + 1st Replicate: Starting temperature was88° C., 0.5% Lactic Acid + ending at 91.5° C. Steam 2nd Replicate:Starting temperature was 86.7° C., ending at 90+?° C. 3rd and 4thReplicates: Temperatures were not recorded. An 8 second exposure timeand a 10 second sterile water rinse utilized for all replicates. 0.5%Lactic Acid + 1st Replicate: Starting temperature was 84° C., Steamending at 88° C. 2nd Replicate: Starting temperature was not recorded,however the ending temperature was 91° C. 3rd Replicate: Temperatureswere not recorded. An 8 second exposure time and a 10 second sterilewater rinse were utilized for all replicates.

Total Plate Count Results Test Formula #1 3.3 × 10⁴ 7.7 × 10³ .80 at 200ppm Test Formula #1 2.0 × 10⁵ 1.7 × 10⁴ 1.08 at 200 ppm + 0.5% LacticAcid Test Formula #1 4.4 × 10⁴ 1.2 × 10³ 1.31 at 200 ppm + 1.0% LacticAcid 0.5% Lactic 2.7 × 10⁴ 5.4 × 10³ 0.91 Acid Steam Alone 1.2 × 10⁴ 2.4× 10³ 1.10 with Sterile Water Rinse Steam + Test 1.5 × 10⁴ 8.4 × 10²1.51 Formula #1 at 200 ppm with Sterile Water Rinse Steam + Test Formula#1 3.1 × 10⁵ 2.6 × 10³ 2.55 at 200 ppm + 0.5% Lactic Acid With SterileWater Rinse Steam + 0.5% Lactic 2.5 × 10⁴ 9.3 × 10² 1.69 Acid withSterile Water Rinse

Conclusions:

The application of Steam with Test Formula #1 at 200 ppm in combinationwith 0.5% Lactic Acid outperformed all other treatments by achieving anaverage of a 2.55 log₁₀ reduction on the surface of prerigor meat. Steamalone, provided an average 1.10 log₁₀ reduction with temperaturesranging from 80-92° C. Test Formula #1 at 200 ppm in combination with0.5% Lactic Acid only provided an average 1.10 log₁₀ reduction incomparison to an average 1.31 log₁₀ reduction in combination with 1.0%Lactic Acid.

The purpose of the remaining working examples was to determine if theuse of higher spray pressures, particularly those above 100 psi, wouldincrease the antimicrobial efficacy of the compositions of theinvention.

Working Example #2

The objective of the testing was to determine the efficacy of variousantimicrobial treatments with extended spray and exposure times againstthe bacterial flora of prerigor beef.

Test Method/Parameters:

Prerigor beef samples were obtained and kept in a cooler at ambienttemperature until time of testing. Ten different test treatments wereutilized with four replicates per treatment. Two cores (4.3 cm diameter)were taken as each replicate from one piece for both before- andafter-treatment samples and combined into 99 mL of Letheen Broth. Thecores/neutralizer mixtures were stomached for 1 minute and then seriallydiluted and plated using pour plate technique.

Test Products:

Test Formula #1* at 200 ppm Peracid=0.42% (4.2 mL were added to 995 .8mL tap water)

Test Formula #1* at 500 ppm Peracid (10.5 mL were added to 989.5 mL tapwater)

0.5% Lactic Acid

* Test Formula #1, batch # Si120972, was titrated at 4.76% totalperacid.

Application: Eight cores (2 cores per replicate) were placed onto aclean and sanitary screen. The cores were sprayed with the appropriatetest product utilizing a 10- or 30-second spray application time. Foreach replicate, two cores were removed after a 10-minute exposure timeand placed into a stomacher bag containing 99 mL of neutralizer.

Neutralizer: 99 mL Letheen Broth

Dilutions: 10⁰, 10⁻¹, 10⁻² for Total Plate Count Before

10⁰, 10⁻¹ for Total Plate Count After

Plating Medium: Tryptone Glucose Extract Agar

Incubation: 26° C. for 72 hours

Calculations: Average CFU/plate=(All eight counts from fourreplicates/4)

Average CFU/plate×100=Average CFU/100 mL=Y${{Average}\frac{CFU}{{cm}^{2}}} = \frac{Y}{2\pi \quad r^{2}}$

Dilution=10, 100, or 1000

r=2.15 cm

2=#of cores

Water Control 3.6 × 10⁴ 4.7 × 10⁴ 0.05 98° F. 25 psi pressure, 10 sec.spray Water Control 1.2 × 10⁵ 1.9 × 10⁵ −0.21  120° 50 psi pressure, 30sec. spray 0.5% Lactic Acid 1.6 × 10⁴ 1.5 × 10⁴ −0.01  98° F. 25 psipressure, 10 sec spray 0.5% Lactic Acid 1.0 × 10⁵ 8.4 × 10⁴ 0.07 120° F.25 psi pressure, 10 sec. spray Test Formula #1 at 200 ppm 2.3 × 10⁴ 8.7× 10³ 0.41 Peracid 90° F. 50 psi pressure, 10 sec spray Test Formula #1at 200 ppm 1.5 × 10⁵ 1.6 × 10⁴ 0.97 Peracid 120° F. 50 psi pressure, 10sec spray Test Formula #1 at 200 ppm 9.0 × 10⁴ 3.9 × 10⁴ 0.37 Peracid120° F. 50 psi pressure, 30 sec spray Test Formula #1 at 200 ppm 6.5 ×10⁵ 6.4 × 10⁵ 0.01 Peracid  1.9 × 10⁴*  1.65* 120° 25 psi pressure, 30sec spray Test Formula #1 at 500 ppm 4.5 × 10⁴ 5.3 × 10³ 0.93 Peracid98° F. 25 psi pressure, 30 sec. spray Test Formula #1 at 500 ppm 4.9 ×10 ⁴ 1.1 × 10⁴ 0.67 Peracid 120 ° F. 25 psi pressure, 10 sec. spray*Average and Log₁₀ Reduction not including replicate #3.

Conclusions:

Overall, the highest reductions in the bacteria flora on the surface ofprerigor beef were seen with the following treatments:

Test Formula #1 at 200 ppm total peracid at 50 psi pressure with a10-second spray time at 120° F. achieved an average 0.97 log₁₀reduction.

Test Formula #1 at 500 ppm total peracid at 25 psi pressure with a30-second spray at 98° F. achieved an average 0.93 log₁₀ reduction.

In regard to temperature, 120° F. resulted in higher efficacy with TestFormula #1 at 200 ppm total peracid at 50 psi pressure with a 10-secondspray time, with a 0.97 log₁₀ reduction versus a 0.41 log₁₀ reduction at98° F.

Working Example #3

The objective of the testing was to determine the efficacy of TestFormula #1 at 200 ppm total peracid with a high pressure applicationspray at 100° F. against the bacterial flora of prerigor beef.

Test Method/Parameters:

Prerigor beef samples were obtained and kept in a cooler at ambienttemperature until time of testing. Four different test treatments wereutilized with four replicates per treatment Two cores (4.3 cm diameter)were taken as each replicate from one piece for both before and aftertreatment samples and combined into 99 mL of Letheen Broth. Thecores/neutralizer mixtures were stomached for 1 minute and then seriallydiluted and plated using pour plate technique.

Test Product: Test Formula #1 at 200 ppm total peracid (Batch #Si120972, was titrated at 4.76% total peracid)

Application: Eight cores (2 cores per replicate) were asepticallyremoved from each sample before treatment. These were used for thebefore treatment samples. The remaining sample was placed onto a cleanand sanitary screen. The sample was then sprayed with Vortex atapproximately 200 ppm total peracid utilizing a 5-, 10- or 30-secondspray application time. For each replicate, two cores were removed aftera 10-minute exposure time and placed into a stomacher bag containing 99mL of neutralizer.

Neutralizer: 99 mL Letheen Broth

Dilutions: 10⁰, 10⁻¹, 10⁻² for Total Plate Count Before

10⁰, 10⁻¹ for Total Plate Count After

Plating Medium: Tryptone Glucose Extract Agar

Incubation: 26° C. for 72 hours

Calculations: Average CFU/plate=(All eight counts from fourreplicates/4)

Average CFU/plate×100 Average CFU/100 mL=Y${{Average}\frac{CFU}{{cm}^{2}}} = \frac{Y}{2\pi \quad r^{2}}$

Dilution=10, 100, or 1000

r=2.15 cm

2=# of cores

Water Control  5.6 × 10 ⁵  2.7 × 10⁴  1.31 ˜230 psi pressure, 30 sec.spray Test Formula #1 at 200 ppm ˜1.9 × 10⁶ ˜2.1 × 10⁵ ˜0.96 Peracid˜230 psi pressure, 10 sec spray Test Formula #1 at 200 ppm ˜2.8 × 10⁶ 2.0 × 10⁵  1.15 Peracid ˜230 psi pressure, 5 sec spray Test Formula #1at 200 ppm  2.1 × 10⁶ <100 >2.90 Peracid ˜230 psi pressure, 30 sec spray

Conclusions:

Test Formula #1 at 200 ppm peracid with a 30-second exposure timeutilizing a high-pressure spray of 230 psi at the nozzle with a distanceof approximately 75 cm achieved the highest reduction with <3.4 CFU/cm²surviving after a 10-minute exposure time at ˜110° F. Utilizing thisprocedure, a>2.90 log reduction was achieved.

Working Example #4

The objective of the testing was to determine the efficacy of TestFormula #1 at approximately 50, 100 and 200 ppm total peracid with ahigh pressure application spray at elevated temperatures in comparisonto Lactic Acid against the bacterial flora of prerigor beef.

Test Method Parameters:

Prerigor beef samples were obtained and kept in a cooler at ambienttemperature until time of testing. Four different test treatments wereutilized with four replicates per treatment. Two cores (4.3 cm diameter)were taken as each replicate from one piece for both before- andafter-treatment samples and combined into 99 mL of Letheen Broth. Thecores/neutralizer mixtures were stomached for 1 minute and then seriallydiluted and plated using pour plate technique.

Test Product: Test Formula #1 at 50, 100 and 200 ppm total peracid

Lactic Acid (88% concentrate)

(Batch # Si120972, was titrated at 4.76% total peracid)

Application: Eight cores (2 cores per replicate) were asepticallyremoved from each sample before treatment. These were used for thebefore-treatment samples. The remaining sample was placed onto a cleanand sanitary screen. The sample was then sprayed with Test Formula #1 atapproximately 50, 100 or 200 ppm total peracid utilizing a 20- or30-second spray application time. 0.5% Lactic Acid utilized only the30-second spray application time. For each replicate, two cores wereremoved after a 10-minute exposure time and placed into a stomacher bagcontaining 99 mL of neutralizer.

Neutralizer: 99 mL Letheen Broth

Dilutions: 10⁰, 10⁻¹, 10⁻² for Total Plate Count before

10⁰, 10⁻¹ for Total Plate Count After

Plating Medium: Tryptone Glucose Extract Agar

Incubation: 16° C. for 72 hours

Calculations: Average CFU/plate=(All eight counts from fourreplicates/4)

Average CFU/plate×100=Average CFU/100 mL=Y${{Average}\frac{CFU}{{cm}^{2}}} = \frac{Y}{2\pi \quad r^{2}}$

Dilution=10, 100 or 10000

r=2.15 cm

2=# of cores

Test Formula #1 at 200 ppm Peracid 3.7 × 10⁴ <100 >2.58  ˜230 psipressure, 30 sec. spray Test Formula #1 at 200 ppm Peracid 3.1 × 10⁵ 3.3× 10³  2.00 ˜230 psi pressure 20 sec. spray Test Formula #1 at 100 ppmPeracid 1.3 × 10⁶ 7.9 × 10³   2.22 ˜230 psi pressure, 30 sec. spray TestFormula #1 at 100 ppm Peracid 2.0 × 10⁵ 4.3 × 10²  2.66 ˜230 psipressure 20 sec. spray Test Formula #1 at 50 ppm Peracid 3.1 × 10⁵ 6.3 ×10³  1.70 ˜230 psi pressure, 30 sec spray Test Formula #1 at 200 ppmPeracid 2.1 × 10⁵ 8.7 × 10⁴  0.38 ˜65 psi pressure 30 sec. spray ˜0.5%Lactic Acid 8.7 × 10⁵ 2.3 × 10⁴  1.58 ˜230 psi pressure, 30 sec. spray

Conclusions:

Test Formula #1 at 200 ppm total peracid sprayed for 30 seconds at ˜230psi pressure achieved the highest reduction of bacteria present on thesurface of prerigor meat with a >2.58 log₁₀ reduction. Test Formula #1at 200 ppm sprayed for 30 seconds at ˜65 psi pressure only achieved anaverage 0.38 log₁₀ reduction.

Working Example #5

The objective of the testing was to determine the efficacy of TestFormula #1 and Lactic Acid against Listeria innocua ATCC 33090 with ahigh-pressure application spray at elevated temperatures.

Test Method/Parameters:

Prerigor beef samples were obtained and kept in a cooler at ambienttemperature until time of testing. Samples were cut into 13 cm piecesand 2.0 mL of the inoculum (see Test System Preparation below) wasspread evenly over the entire surface of the sample. Inoculated sampleswere then left at room temperature (˜23° C.) for ≧15 minutes. Fourreplicate samples were taken (two cores per replicate) before treatment.After each spray treatment, a 10-minute exposure time was utilized, andtahen four replicate samples were taken (two cores per replicate) andstomached for 1 minute, serially diluted and plated using pour platetechnique.

Treatments:

1. Test Formula #1 at 200 ppm total peracid with ˜psi pressure spray, 30second spray time.

2. Test Formula #1 at 200 ppm total peracid with ˜150 psi pressurespray, 30 second spray time.

3. Test Formula #1 at 200 ppm total peracid with ˜100 psi pressurespray, 30 second spray time.

4. Water Control with ˜220 psi pressure spray, 30-second spray time.

5. ˜0.5% -0.75% Lactic Acid with ˜220 psi pressure spray, 30-secondspray time.

6. Test Formula #1 at 100 ppm total peracid with ˜220 psi pressurespray, 30 second spray time.

7. Test Formula #1 at 200 ppm total peracid with ˜220 psi pressurespray, 15 second spray time.

* Tiration of the Lactic Acid solution used 12 drops of 1N SodiumHydroxide for the indicator color change. In preliminary titrations of a0.5% Lactic Acid solution, 7 drops of 1N Sodium Hydroxide were needed.Therefore, the sample was estimated to be at a concentration between0175% and 1.0% Lactic Acid.

Test Temperature: ˜120° F.

Test System: Listeria innocua ATCC 33090

Test System

Preparation: 25 grams of sterilized cow feces was added into 50 grams ofsterile phosphate buffered dilution water and stomached for 1 minute.60.0 grams from this fecal slurry was transferred to a sterile stomacherbag and 6.0 mL of an ˜10⁸ CFU/mL Listeria innocua 24-hour broth culture(grown in BHI broth at 37° C.) was added and mixed. This inoculum wastherefore estimated at 10⁷ CFU/mL, which yielded approximately 10⁵CFU/cm².

Exposure Time: 10 minutes

Neutralizer: 99 mL Letheen Broth

Dilutions: 10⁻⁴, 10⁻⁵, 10¹⁶ (for Before Treatment, Inoculation Numberssamples)

10⁰, 10⁻¹, 10⁻² (After Treatment samples)

Plating Medium: Listeria Selective Agar

Incubation: 26° for 72 hours

Calculations: Average CFU/plate=(All eight counts from fourreplicates/4)

Average CFU/plate×100=Average CFU/100 mL=Y${{Average}\frac{CFU}{{cm}^{2}}} = \frac{Y}{2\pi \quad r^{2}}$

r=2.15 cm 2=# of cores

Test Formula #1 at 200 ppm 1.6 × 10⁵ 1.97 Peracid ˜220 psi pressure 30second spray* Test Formula #1 at 200 ppm 5.1 × 10⁴ 2.45 Peracid ˜150 psipressure 30 second spray* Test Formula #1 at 200 ppm 1.4 × 10⁵ 2.03Peracid ˜100 psi pressure 30 second spray* Water Control 4.9 × 10⁵ 1.48˜220 psi pressure 30 second spray Lactic Acid 3.5 × 10⁵ 1.63 ˜220 psipressure 30 second spray Test Formula #1 at 100 ppm 1.6 × 10⁵ 1.97Peracid ˜220 psi pressure 30 second spray* Test Formula #1 at 200 ppmPeracid ˜100 psi pressure 2.2 × 10⁵ 1.83 15 second spray*

Conclusions:

Treatment at 200 ppm peracid with an ˜150 psi spray for 30 secondsachieved an average 2.45 log₁₀ reduction of Listeria innocua ATCC 33090.Lactic Acid achieved a 1.63 log₁₀ reduction of this organism which wasonly slightly higher than the water control which achieved an average1.48 log₁₀ reduction.

The above discussion, examples, and data illustrate our currentunderstanding of the invention. However, since many variations of theinvention can be made without departing form the spirit and scope of theinvention, the invention resides in the claims hereinafter appended.

We claim:
 1. A method of reducing a microbial population on poultry during processing comprising: applying to the poultry during processing a mixed peroxycarboxylic acid antimicrobial composition in an amount and time sufficient to reduce the microbial population.
 2. The method of claim 1, wherein the poultry being processed comprises chicken, turkey, ostrich, game hen, squab, or pheasant.
 3. The method of claim 1, comprising applying the mixed peroxycarboxylic acid composition by immersing the poultry.
 4. The method of claim 3, comprising immersing the poultry in a heated mixed peroxycarboxylic acid composition.
 5. The method of claim 3, further comprising agitating the mixed peroxycarboxylic acid composition.
 6. The method of claim 1, comprising applying the mixed peroxycarboxylic acid composition by spraying the poultry.
 7. The method of claim 1, comprising applying the mixed peroxycarboxylic acid composition to a whole poultry carcass.
 8. The method of claim 1, comprising applying the mixed peroxycarboxylic acid composition to cut poultry meat.
 9. The method of claim 1, further comprising exposing the poultry to activating light.
 10. The method of claim 9, wherein the activating light comprises ultraviolet light, infrared light, visible light, or a combination thereof.
 11. The method of claim 1, wherein the mixed peroxycarboxylic acid composition comprises peroxyacetic acid and peroxyoctanoic acid.
 12. The method of claim 1, wherein the mixed peroxycarboxylic acid antimicrobial composition comprises: at least about 2 ppm of one or more mono- or di-peroxycarboxylic acids having up to 12 carbon atoms; and at least 0.5 ppm of one or more carboxylic acids having up to 18 carbon atoms.
 13. The method of claim 12, wherein the mixed peroxycarboxylic acid composition comprises one or more peroxycarboxylic acids having from 2 to 4 carbon atoms and a peroxycarboxylic acid having from 8 to 12 carbon atoms.
 14. The method of claim 13, wherein the mixed peroxycarboxylic acid composition comprises peroxyacetic acid and peroxyoctanoic acid.
 15. The method of claim 1, wherein the antimicrobial composition comprises about 2 to 25 parts by weight of hydrogen peroxide per each one million parts of the composition.
 16. The method of claim 1, wherein the mixed peroxycarboxylic acid antimicrobial composition further comprises chelating agent, hydrotrope, foaming agent, thickener, gelling agent, or a combination thereof.
 17. The method of claim 1, wherein the population reduction comprises at least one log₁₀ reduction in the microbial population.
 18. The method of claim 1, wherein the population reduction comprises at least two log₁₀ reduction in the microbial population.
 19. The method of claim 1, wherein the population reduction comprises at least three log₁₀ reduction in the microbial population.
 20. The method of claim 1, wherein the population comprises a human pathogen.
 21. The method of claim 1, wherein the population comprises Escherichia coli.
 22. The method of claim 6, further comprising moving the surface of the carcass with mechanical action.
 23. The method of claim 22, wherein moving comprises agitating, rubbing, scrubbing, brushing, or combination thereof.
 24. The method of claim 6, comprising spraying in a spray booth.
 25. The method of claim 24, further comprising moving the poultry along a production line and through the spray booth.
 26. The method of claim 6, comprising spraying a foaming composition or spraying a thickened or gelled composition. 